rough idle in drive 190E
 

Car idles right in park and neutral and reverse...smooth, but when shifted to drive, 3rd, or 2nd it idles rough. Have read all the threads on this but nothing seems to help. Have done the
idle control valve, and have checked for vacuum leaks. Give me
some input...will let everyone know what I've done and am doing.

Have you checked your engine mounts?

Vin

When you say rough, is it missing?

Motor mounts seems OK...the engine idles smooth in Park, Neutral, and Reverse...like glass 750RPM, but when shifted to drive the whole car shakes...almost acts like the converter not disengaging, but it is...thought maybe with foot on the brake I had a vacuum leak, but checked the vacuum hose to the brake and do not like anything wrong. Keep up the input. Thanks

How do I check motor mounts...other than looking for cracks and checks. Car has 100M+ do you change them as maintance.

If the car still has the original mounts they are more than likely shot.
The proper way of checking is to measure mount height. If you don't have the specs, the best thing is to do a visual check. The obvious is to look around for cracks. Get a mirror if needed (especially driver's side) and look around the top for any signs of cracking. Check for any oil leaks around or under mount. They always leave a trace usually a white, yellow, or rust color. You can also try lifting engine by placing a piece of wood at the mount arm and checking if the mount separates.
Don't forget to check rear transmission mount. Check for separation by using a pry bar.

Vin

will check the motor mounts tomorrow 4/9/02 and let everybody know what I find. Why does it not vibrate in reverse? ... like it does in the forward gears.

190 2.6, 1991 rough idle when hot in my car too
 

hi,

looks like i have a fairly similar situation with the rough idle. happens only when car is hot, cold engine/starting is fine. when hot (80 to 100F), the idle speed in gear drops to 500rpm. have changed distributor rotor, cap, plugs, thermostat, coolant, and coolant temp sensor (since a couple of mechanics told me the engine maybe running hot.) all these things didn't really help. would appreciate your input.......could it be the ignition wire set or gas filter? the car's got 139K

when i drive, the car has plenty of pep and drives real smooth and well.

i test drove a (certified pre-owned) 94 C280 today at a mercedes dealership and that car had the same problem.

i am wondering if this is a wide-spread problem, and the possible causes.

also, any pointers on what the temp range should be - how can i tell if the engine is running hot and why?

Many thanks!

Thanks for getting in on the discussion. My car shakes at idle in drive only...it is smooth in park reverse and neutral. Also my car
does not heat up...tack welded the broken clutch fan so is runs all the time. Never over 80C maybe hotter in summer don't know.

Just cam across 190E motor mounts in Preformance Paddack...this seems to be what I will do and then let you know.
Did not find this thread using "Search" ...couldn't, alway showed no matches.

thanks for the clarification. my car shook in drive also. but i think i just might have lucked out on finding the solution to my problem - still cant believe it though! the ignition wire to the 6th cylinder was simply loose and upon getting hot, the spark wasn't going across smoothly. wonder why none of the mechanics didn't catch this simple loose contact! the car is now not going beyond about 85degrees and is smoother. i hope this was the only problem, i guess time will tell, but i sure am excited for now!

had a brainwave for your problem.......when i bought this used car, it was shaking very badly when i put it in gear. turned out that the coupling / mount / o-ring on the axle was cracked. i remember seeing two of these circular couplings - one in front and another one at the back. i think there's also a mount sort of a thing toward the rear of the drive shaft. you may wanna lift the car and inspect these items for cracks, these things look very flimsy to begin with.

good luck

i had the same shuddering problem in my 87 190 with 300k on it... it was the rear trasmission mount. 40$ part, and you can do it yourself.